Umbrella and fuel cell: what they have in common

1. Step 1. Umbrella — is made of — Silk. The canopy is made of silk.
2. Step 2. Silk — is material for — Hot air balloon. The Montgolfier balloon was fabric lined with paper.
3. Step 3. Hot air balloon — evolved into — Airship. A steerable balloon.
4. Step 4. Airship — uses — Hydrogen. Zeppelins were filled with hydrogen.
5. Step 5. Hydrogen — is used in — Fuel cell. The fuel is hydrogen.

Open Evothings